The Arabidopsis defensin gene AtPDF2.5 mediates cadmium tolerance and accumulation
The Arabidopsis defensin gene AtPDF2.5 mediates cadmium tolerance and accumulation
复制标题
拟南芥防御素基因AtPDF2.5介导镉耐受和积累
DOI：
10.1111/pce.13592
复制
发表时间：
2019-09-01
影响因子：
7.3
通讯作者：
Zhang, Zhenhua
中科院分区：
文献类型：
--
作者：
Luo, Jin-Song;Yang, Yong;Zhang, Zhenhua
虽然过量的镉（Cd）积累对植物有害，但拟南芥中Cd解毒和积累的分子机制仍然很不确定。在这项研究中，我们证明了A.拟南芥植物防御素2基因AtPDF2.5参与镉耐受和积累。体外镉结合实验表明AtPDF2.5具有镉螯合活性。AtPDF2.5的定点突变确定了8个半胱氨酸残基，这是必不可少的介导镉耐受性和螯合。组织化学分析表明，AtPDF2.5主要在根木质部维管束中表达，Cd对AtPDF2.5的表达有明显的诱导作用。亚细胞定位分析显示AtPDF2.5定位于细胞壁。AtPDF2.5的过表达显着增强了A.拟南芥及其在水稻中的异源过表达增加了Cd的积累;然而，AtPDF2.5的功能破坏降低了Cd的耐受性和积累。生理分析表明，AtPDF2.5促进镉流出原生质体和随后的积累在细胞壁中。这些数据表明，AtPDF2.5通过螯合作用促进细胞质镉流出，从而提高镉解毒和质外体积累。
Although excess cadmium (Cd) accumulation is harmful to plants, the molecular mechanisms underlying Cd detoxification and accumulation in Arabidopsis thaliana remain largely undetermined. In this study, we demonstrated that the A. thaliana PLANT DEFENSIN 2 gene AtPDF2.5 is involved in Cd tolerance and accumulation. In vitro Cd-binding assays revealed that AtPDF2.5 has Cd-chelating activity. Site-directed mutagenesis of AtPDF2.5 identified eight cysteine residues that were essential for mediating Cd tolerance and chelation. Histochemical analysis demonstrated that AtPDF2.5 was mainly expressed in root xylem vascular bundles, and that AtPDF2.5 was significantly induced by Cd. Subcellular localization analysis revealed that AtPDF2.5 was localized to the cell wall. The overexpression of AtPDF2.5 significantly enhanced Cd tolerance and accumulation in A. thaliana and its heterologous overexpression in rice increased Cd accumulation; however, the functional disruption of AtPDF2.5 decreased Cd tolerance and accumulation. Physiological analysis suggested that AtPDF2.5 promoted Cd efflux from the protoplast and its subsequent accumulation in the cell wall. These data suggest that AtPDF2.5 promotes cytoplasmic Cd efflux via chelation, thereby enhancing Cd detoxification and apoplastic accumulation.